Dynamics of the α-relaxation in glass-forming polymeric systems. Study by neutron scattering and relaxation techniques

Abstract

The dynamics of the α-relaxtion in three glass-forming polymeric systems has been studied by means of quasielastic neutron scattering as well as by relaxation techniques. By using these techniques, we have covered a wide time-scale ranging from mesoscopic to macroscopic times (10⁻¹⁰–10¹ s). All relaxation data have been interpreted in terms of a Havriliak-Nagami relaxation function, Φ _HN. Neutron scattering data were described in terms of a scattering law S(Q, ω) which was also built starting from Φ _HN. The results obtained indicate that the dynamics of the α-relaxation in a wide timescale can be well described by means of the same spectral shape, i.e. the same Havriliak-Negami parameter values. Moreover, the Havriliak-Negami characteristic times deduced from the fitting of the experimental data can also be described using only one Vogel-Fulcher functional form. Then, this implies a self-consistent description of the dynamics of the α-relaxation obtained by very different probes.